'use strict'
module.exports = rfdc

function copyBuffer(cur) {
    if (cur instanceof Buffer) {
        return Buffer.from(cur)
    }

    return new cur.constructor(cur.buffer.slice(), cur.byteOffset, cur.length)
}

function rfdc(opts) {
    opts = opts || {}
    if (opts.circles) return rfdcCircles(opts)

    const constructorHandlers = new Map()
    constructorHandlers.set(Date, (o) => new Date(o))
    constructorHandlers.set(Map, (o, fn) => new Map(cloneArray(Array.from(o), fn)))
    constructorHandlers.set(Set, (o, fn) => new Set(cloneArray(Array.from(o), fn)))
    if (opts.constructorHandlers) {
        for (const handler of opts.constructorHandlers) {
            constructorHandlers.set(handler[0], handler[1])
        }
    }

    let handler = null

    return opts.proto ? cloneProto : clone

    function cloneArray(a, fn) {
        const keys = Object.keys(a)
        const a2 = new Array(keys.length)
        for (let i = 0; i < keys.length; i++) {
            const k = keys[i]
            const cur = a[k]
            if (typeof cur !== 'object' || cur === null) {
                a2[k] = cur
            } else if (cur.constructor !== Object && (handler = constructorHandlers.get(cur.constructor))) {
                a2[k] = handler(cur, fn)
            } else if (ArrayBuffer.isView(cur)) {
                a2[k] = copyBuffer(cur)
            } else {
                a2[k] = fn(cur)
            }
        }
        return a2
    }

    function clone(o) {
        if (typeof o !== 'object' || o === null) return o
        if (Array.isArray(o)) return cloneArray(o, clone)
        if (o.constructor !== Object && (handler = constructorHandlers.get(o.constructor))) {
            return handler(o, clone)
        }
        const o2 = {}
        for (const k in o) {
            if (Object.hasOwnProperty.call(o, k) === false) continue
            const cur = o[k]
            if (typeof cur !== 'object' || cur === null) {
                o2[k] = cur
            } else if (cur.constructor !== Object && (handler = constructorHandlers.get(cur.constructor))) {
                o2[k] = handler(cur, clone)
            } else if (ArrayBuffer.isView(cur)) {
                o2[k] = copyBuffer(cur)
            } else {
                o2[k] = clone(cur)
            }
        }
        return o2
    }

    function cloneProto(o) {
        if (typeof o !== 'object' || o === null) return o
        if (Array.isArray(o)) return cloneArray(o, cloneProto)
        if (o.constructor !== Object && (handler = constructorHandlers.get(o.constructor))) {
            return handler(o, cloneProto)
        }
        const o2 = {}
        for (const k in o) {
            const cur = o[k]
            if (typeof cur !== 'object' || cur === null) {
                o2[k] = cur
            } else if (cur.constructor !== Object && (handler = constructorHandlers.get(cur.constructor))) {
                o2[k] = handler(cur, cloneProto)
            } else if (ArrayBuffer.isView(cur)) {
                o2[k] = copyBuffer(cur)
            } else {
                o2[k] = cloneProto(cur)
            }
        }
        return o2
    }
}

function rfdcCircles(opts) {
    const refs = []
    const refsNew = []

    const constructorHandlers = new Map()
    constructorHandlers.set(Date, (o) => new Date(o))
    constructorHandlers.set(Map, (o, fn) => new Map(cloneArray(Array.from(o), fn)))
    constructorHandlers.set(Set, (o, fn) => new Set(cloneArray(Array.from(o), fn)))
    if (opts.constructorHandlers) {
        for (const handler of opts.constructorHandlers) {
            constructorHandlers.set(handler[0], handler[1])
        }
    }

    let handler = null
    return opts.proto ? cloneProto : clone

    function cloneArray(a, fn) {
        const keys = Object.keys(a)
        const a2 = new Array(keys.length)
        for (let i = 0; i < keys.length; i++) {
            const k = keys[i]
            const cur = a[k]
            if (typeof cur !== 'object' || cur === null) {
                a2[k] = cur
            } else if (cur.constructor !== Object && (handler = constructorHandlers.get(cur.constructor))) {
                a2[k] = handler(cur, fn)
            } else if (ArrayBuffer.isView(cur)) {
                a2[k] = copyBuffer(cur)
            } else {
                const index = refs.indexOf(cur)
                if (index !== -1) {
                    a2[k] = refsNew[index]
                } else {
                    a2[k] = fn(cur)
                }
            }
        }
        return a2
    }

    function clone(o) {
        if (typeof o !== 'object' || o === null) return o
        if (Array.isArray(o)) return cloneArray(o, clone)
        if (o.constructor !== Object && (handler = constructorHandlers.get(o.constructor))) {
            return handler(o, clone)
        }
        const o2 = {}
        refs.push(o)
        refsNew.push(o2)
        for (const k in o) {
            if (Object.hasOwnProperty.call(o, k) === false) continue
            const cur = o[k]
            if (typeof cur !== 'object' || cur === null) {
                o2[k] = cur
            } else if (cur.constructor !== Object && (handler = constructorHandlers.get(cur.constructor))) {
                o2[k] = handler(cur, clone)
            } else if (ArrayBuffer.isView(cur)) {
                o2[k] = copyBuffer(cur)
            } else {
                const i = refs.indexOf(cur)
                if (i !== -1) {
                    o2[k] = refsNew[i]
                } else {
                    o2[k] = clone(cur)
                }
            }
        }
        refs.pop()
        refsNew.pop()
        return o2
    }

    function cloneProto(o) {
        if (typeof o !== 'object' || o === null) return o
        if (Array.isArray(o)) return cloneArray(o, cloneProto)
        if (o.constructor !== Object && (handler = constructorHandlers.get(o.constructor))) {
            return handler(o, cloneProto)
        }
        const o2 = {}
        refs.push(o)
        refsNew.push(o2)
        for (const k in o) {
            const cur = o[k]
            if (typeof cur !== 'object' || cur === null) {
                o2[k] = cur
            } else if (cur.constructor !== Object && (handler = constructorHandlers.get(cur.constructor))) {
                o2[k] = handler(cur, cloneProto)
            } else if (ArrayBuffer.isView(cur)) {
                o2[k] = copyBuffer(cur)
            } else {
                const i = refs.indexOf(cur)
                if (i !== -1) {
                    o2[k] = refsNew[i]
                } else {
                    o2[k] = cloneProto(cur)
                }
            }
        }
        refs.pop()
        refsNew.pop()
        return o2
    }
}